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When good rivers turn bad: Extreme flooding
Case study - The Johnstone River, Far North Queensland

Interpreting warnings and river heights

Flood Warnings and River Height Bulletins contain observed river heights for a selection of the river height monitoring locations. The time at which the river reading has been taken is given together with its tendency (e.g. rising, falling, steady or at its peak). The Flood Warnings may also contain predictions in the form of minor, moderate or major flooding for a period in the future. River Height Bulletins also give the height above or below the road bridge or causeway for each river station located near a road crossing.

One of the simplest ways of understanding what the actual or predicted river height means is to compare the height given in the Warning or Bulletin with the height of previous floods at that location.

The table below summarises the flood history of the Johnstone River catchment - it contains the flood gauge heights of the highest know floods recorded at selected river height locations, together with heights of recent floods.

River
height
station
Highest Recorded Flood 
(in metres)
Mar
1967
Apr
1982
Feb
1986
Mar
1997
Feb
1999
Nerada Feb
1999
11.15       10.30 11.15
Tung Oil Feb
1999
10.81  10.33 10.19  10.17 9.34 10.81
Corsis Mar
1997
6.68        6.68 6.68
Central Mill Mar
1967
11.13*  11.13*  8.10  10.84 9.85 9.70
Innisfail -
1913
8.09* 6.25* 5.81* 6.42* 5.85 6.37

All heights are in metres on flood gauges.
[*] These heights are taken at old gauge sites and may not relate to flood levels from existing gauges sites.

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1. Origins of extreme weather | 2. Finding hidden treasure | 3. Streams and mass wasting
4. The Johnstone River, FNQ


The resources contained in this unit are courtesy of Earth Science Australia http://earthsci.org/